Polymer-based films, fibers or filament structures have been adapted for widespread use in many different applications, such as nonwoven sheets which can be made into a variety of wipers, disposable absorbent products, or protective and healthcare related fabrics. For example, in the infant and child care areas, diapers and training pants have generally replaced reusable cloth absorbent articles. Other typical disposable absorbent products include feminine care products such as sanitary napkins or tampons, adult incontinence products, and health care products such as surgical drapes or wound dressings. A typical disposable absorbent product generally comprises a composite structure including a topsheet, a backsheet, and an absorbent structure between the topsheet and backsheet. These products usually include some type of fastening system for fitting the product onto the wearer.
Disposable absorbent products are typically subjected to one or more liquid insults, such as of water, urine, menses, or blood, during use. As such, the outer cover backsheet materials of the disposable absorbent products are typically made of liquid-insoluble and liquid impermeable materials, such as polyethylene films, that exhibit a sufficient strength and handling capability so that the disposable absorbent product retains its integrity during use by a wearer and does not allow leakage of the liquid insulting the product.
Although current disposable baby diapers and other disposable absorbent products have been generally accepted by the public, these products still have a need of improvement in specific areas. Many disposable absorbent products can be difficult to be compatible with existing waste disposal systems. For example, attempts to flush many disposable absorbent cores or products down a toilet into a sewage system typically lead to blockage of the toilet or pipes connecting the toilet to the sewage system. In particular, the outer cover materials typically used in the disposable absorbent products generally do not disintegrate or disperse when flushed down a toilet so that the disposable absorbent product cannot be disposed of in this way. If the outer cover materials are made very thin in order to reduce the overall bulk of the disposable absorbent product so as to reduce the likelihood of blockage of a toilet or a sewage pipe, then the outer cover material typically will not exhibit sufficient strength to prevent tearing or ripping as the outer cover material is subjected to the stresses of normal use by a wearer.
Furthermore, solid waste disposal is becoming an ever-increasing concern throughout the world. As landfills continue to fill up, there has been an increased demand for material source reduction in disposable products, the incorporation of more recyclable and/or biodegradable components in disposable products, and the design of products that can be disposed of by means other than in solid waste disposal facilities such as landfills. As such, a need exists for new materials that may be incorporated in disposable absorbent products, which generally retain their integrity and strength during use, but the materials can be disposed of more efficiently after use. For example, the disposable absorbent product may be efficiently disposed of by either composting or a liquid sewage system, in which the disposable absorbent product can be easily degraded.
Over the years, different kinds of algae have been adapted for a variety of industrial applications. For instance, adsorbent materials comprising green algae, such as Chlorella or Spirulina, are adapted to remove toxic and odor in cigarette and air, or using brown algae to remove heavy metals from wastewater with absorbent particle sizes varied from 500 μm˜2 mm. Others have used green algae Chlorella, in combination with a consortium of prokaryptic microorganisms, to effectively purify wastewater effluent streams using a photobioreactor. Researchers have developed methods to identify algae species and compositions that are effective for lipid production, wastewater and air remediation, or biomass production.
Recent work in adapting algae for industrial uses have concentrated on their refinement as biofuels, which is an outgrowth of increasingly limited fossil fuel resources and relative high cost of petroleum. Biomeal, a leftover waste material from algae to biofuel processing, is normally used for animal feeds. (See, e.g., U.S. Pat. No. 6,338,866 and International Patent Publication No. WO 01/60166 to Criggall et al., which developed methods to manufacture pet or animal foods using such a waste product which includes the cell carcasses that remain after one or more essential fatty acids such as docosahexaenoic acid (DHA) have been extracted from lysed algae cells such as Crypthecodinium cohnii; WO Publication No. 2008/039911 to Lo et al. provides a method of optimizing pet food palatable components comprising algal biomeal.)
U.S. Pat. Nos. 5,352,709, 5,779,960, and EP Patent No. 702,703 to Tarrant et al. deal with plastic applications of algal material. Specifically, Tarrant et al. used filamentous algae such as Clodophora glomerata to generate foamed packing materials (e.g. packing peanuts). U.S. Pat. No. 5,654,103 to Troadec used alginate of algal origin, together with an aqueous solvent and a plasticizer to form films. Similarly WO Publication No. 00/11069 to Kunstmann used naturally growing raw materials such as algae for producing at least 3% alginate and further reacting with calcium ion and foaming agent for production of foamed articles for packaging applications. Johnson and Shivkumar (2004) collected Clodophora glomerata and Pithophora oedegonia from rivers and streams in California for making isocynanate-based foams. WO Publication No. 2007/079719 to Koryszczuk dealt with the use algae in composites. U.S. Patent Publication No. 2008/0057547 to You et al. disclosed a method of using red algae—Rhodophyta for manufacturing pulp and paper through immersing algae into an extraction solvent to dissolve agar gel which is then reacted with a reaction solvent that contains oxidizing agents for fiber conversion and pulping. Structurally speaking, red algae are not microalgae, on which this invention is focused. Lee et al. made red algae and poly(butylene succinate) biocomposites using a compression molding technique. (Lee, M. W., Han, S. O., and Seo, Y. B. (2008), Red Algae Fibre/Poly(butylene succinate) Biocomposites: The Effect of Fibre Content on Their Mechanical and Thermal Properties, COMPOSITE SCI. AND TECHNOLOGY, Vol. 68, 1266˜1272.)
Chiellini et al. used green algae, Ulva armoricana, to produce hybrid polyvinyl alcohol-based composites by solution casting and melt processing, respectively. The latter was based on a torque rheometer connected to plastograph to produce pellets containing up to 30% of algae. Soil burial testing was conducted to assess the composite biodegradation. A 70% mineralization of the composite was achieved in about two months. (Chiellini, E., Cinelli, P. LLieva, V. I., and Martera, M. (2008), Biodegradable Thermoplastic Composites Based on Polyvinyl Alcohol and Algae, BIOMACROMOLECULES, Vol. 9, 1007˜1013.)
Several papers by Zhang et al. (2000 a and b), and Otsuki et al. (2004) addressed techniques to incorporate Chlorella, a kind of microalgae belonging to the Chlorophyceae, into polypropylene, polyethylene, and polyvinyl chloride, respectively, to create novel industrial materials. These blends were made by a modification of synthetic polymers and a roller mixer was used obtain composite samples under heat-pressurizing and molding. These steps were tedious in laboratory and not suitable for industrial-wide production such as utilizing an extrusion technology. (Zhang, F., Endo, T., Kitagawa, R., Kabeya, H., and Hirotsu, T. (2000a), Synthesis and Characterization of a Novel Blend of Polypropylene with Chlorella, J. MATER. CHEM., Vol. 10, 2666˜2672; Zhang, F., Kabeya, H., Kitagawa, R., and Hisrotsu, T. (2000b), An Exploratory Research of PVC-Chlorella Composite Material (PCCM) as Effective Utilization of Chloralla Biologically Fixing CO2. J. MATER. SCI., Vol. 35, 2603˜2609; Otsuki, T., Zhang, F., Kabeya, H., and Histosu, T. (2004), Synthesis and Tensile Properties of a Novel Composite of Chorella and Polyethylene, J. APPLIED POLYMER SCI., Vol. 92, 812˜816.)
But in some cases, biomeal is treated as a waste and disposed of in landfills. Therefore, a value-added utilization of the biomeal will be a very attractive approach. Activities in algae production and utilization will increase in the future because there is a need to reduce global warming and cleaning up of wastewater effluent. On the other hand, petroleum-based oil products that predominate in the energy market today are not sustainable. As a result, it is expected that there is a large amount of algae to be used for biofuel refining processes described in U.S. Patent Application Publications 2008/0155888 to Vick et al. and 2008/0090284 to Hazlebeck et al. Biomeal or a leftover material from algae to biofuel refining processes will be abundantly available because the estimated algal meal as a byproduct is 0.77 lb for every pound of algae processed for oil. Therefore, effective utilization of such a waste material in plastic manufacturing become important to any business that is currently depending on petroleum as a feedstock. It is one of renewable material sources, particularly when petroleum diminishes in the future.